\begin{tikzpicture}
    \tkzDefPoints{0/0/B,  3/0/C,  1/2/A,  2.5/2/D}

    \tkzDrawPolygon(A,B,C,D)
    \tkzLabelPoints[left](A, B)
    \tkzLabelPoints[right](C, D)
\end{tikzpicture}

